It is known in recent years to provide on a smartphone, a game machine or the like, a solid-state imaging device, i.e., a so-called distance measuring sensor provided with a distance measuring camera which applies infrared light to an imaging target space, for example, and detects movement of a body or a hand of a subject (human) to capture a distance image used by the smartphone, game machine or the like (for example, see PTL 1).
A solid-state imaging device described in PTL 1 reads signal charges from photoelectric conversion units of adjoining two pixels, and adds the signal charges on a vertical transfer unit to produce three packets (memory cells) for every two pixels. This solid-state imaging device uses a time of flight method (TOF method) as an operation principle of a distance measuring camera. The solid-state imaging device emits pulsed infrared light, and receives reflected light of the infrared light from a subject in two types of exposure periods to read two-types of signal charges S0 and S1 from photoelectric conversion units and accumulate read signal charges S0 and S1 in corresponding packets. In addition, the solid-state imaging device receives background light without emitting infrared light to read signal charge BG and accumulate the signal charge BG in a packet. The signal charges accumulated in the respective packets are sequentially transferred and output to calculate a distance to the subject for each pixel based on ratios and differences between signal charges S0, S1, and BG, and form a distance image based on the calculated distance.
Moreover, according to PTL 1, pixels are disposed in a checkered pattern to improve horizontal and vertical resolutions of the distance image.